A rocker arm includes a pair of side wall portions formed so as to face each other, an engaging portion connecting the pair of side wall portions and adapted to engage with a rocking support member arranged in an engine, and a sliding portion connecting the pair of side wall portions and being adapted to be in slidable contact with a stem front end portion of an engine valve. The engaging portion includes a board surface portion connecting the pair of side wall portions and a protruding portion protruding from the board surface portion toward the rocking support member. In the protruding portion, a spherical concave portion adapted to engage with a spherical protruding portion of the rocking support member is formed as a depression.